1. Technical Field
The present invention relates to an imaging element having a phase difference detection pixel and an imaging apparatus equipped with the imaging element.
2. Related Art
An imaging element such as a CCD type or a CMOS type is configured by arraying pixels, which are photoelectric conversion elements, in a 2D array pattern. FIG. 14A illustrates a plan view of 1 pixel and a light blocking layer 1a is stacked on a rectangular photoelectric conversion element (photodiode, hereinafter, referred to as a pixel) 1 and an opening 1b is provided in the light blocking layer 1a. The opening 1b is formed widely such that a light receiving surface of the pixel 1 may not be covered if possible so as to receive a large amount of light.
The plurality of such pixels 1 is arrayed on a surface of a semiconductor board in the 2D array pattern. However, an imaging element in which a phase difference detection pixel coexists in an array of pixels 1 that captures a subject image has been recently proposed and applied to an actual device.
FIG. 14B is a plan view of one example of a phase difference detection pixel. In a phase difference detection pixel 2, a light blocking layer opening 2b which is narrower than the opening 1b of FIG. 14A is provided to be eccentric to the right with respect to a center of the pixel. In a phase difference detection pixel 3, a narrow light blocking layer opening 3b having the same size as the light blocking layer opening 2b is provided to be eccentric to the left with respect to the center of the pixel.
A pair of the phase difference detection pixels 2 and 3 in which the light blocking layer openings 2b and 3b are displaced horizontally are used to acquire left-right-direction, that is, horizontal incident light phase difference information. In addition, when the phase difference detection pixel pair is arranged horizontally in an imaging element, a horizontal distribution of the phase difference information may be acquired and for example, a focus distance up to a subject may be detected from the distribution information. As a result, the phase difference detection pixels 2 and 3 are used as focus detecting pixels in Patent Literature 1 (JP-A-2011-252955) and Patent Literature 2 (JP-A-2011-242514).
FIG. 15 is a view describing a layout of the phase difference detection pixels disclosed in Patent Literatures 1 and 2. Light blocking layer openings of pixels (referred to as ordinary pixels) other than the phase difference detection pixels are not illustrated. In an imaging element 5 in the related art, ordinary pixels 1 are arrayed in a square lattice shape and all pixels for 1 row within a predetermined range among the ordinary pixels 1 become pairs of the phase difference detection pixels 2 and 3.
When all the pixels for 1 row become the phase difference detection pixel pairs as described above, it is advantageous in that a horizontal resolution of the detected phase difference information is increased.
Although a description has been made above on an example in which the phase difference pixel pair is configured by making the narrow light blocking layer openings 2b and 3b be eccentric to the center of the pixel, one ellipsoidal microlens may be mounted with respect to 2 pixels adjacent to the ordinary pixels 1 to be pupil-divided, which become the phase difference pixel pair.